Our overall objectives are to characterize associations formed between the red cell cytoskeletal proteins spectrin, actin and band 4.1 in solution and when bound to the red cell membrane. We intend to investigate factors which my regulate these associations such as metabolites divalent cations and pH in the hope of gaining insight into the influence that these same factors have upon red blood cell shape and flexibility. Further, we intend to determine how the cytoskeletal protein actin is bound to the red cell membrane by making direct measurements of actin binding to inside-out red cell vesicles. Finally, we will compare the findings we obtain with cytoskeletal proteins from normal red cells with those from patients with hereditary spherocytosis and hereditary eliptocytosis. Our goal will be to determine whether there is a cytoskeletal defect in these diseases and if so whether it is related to the associations between actin, spectrin and band 4.1.